This is interesting albeit I didn't get it to run yet (it's in the repos tho)
Got it running in the systray with `"gxkb &" command (could add that to startup-applications) but don't see a GUI way to add layouts. 
Configuration is a bit of a thing here:
Configuration is done via config file: .config/gxkb/gxkb.cfg
The most interesting options are:
layouts=us,ru,ua
toggle_option=grp:alt_shift_toggle,grp_led:scroll,terminate:ctrl_alt_bksp
Instead of grp:alt_shift_toggle you can use whatever the following command gives you: grep grp:.*toggle /usr/share/X11/xkb/rules/base.lst
Conclusion
we "only" need to make a noob friendly GUI configurator for setting keyboard choices for E16 after pulling-in/installing "gxkb"
i.e write to the gxkb.cfg file what lay-out the users chooses when offered the option and then add gxkb to startup-applications, so as to have it in the systray.
Maybe "yad/zenity" is a better option here as GUI.
